1. Field of the Invention
The present invention relates to an air bag system mounting structure for fixing an instrument panel and a mounting portion of an air bag module.
2. Description of the Related Art
An air bag module for a front-seat passenger is housed in the interior of an instrument panel. For example, the air bag module is supported on a pillar-to-pillar pipe which connects to left and right front pillars.
As a method for fixing to position a lower surface of the instrument panel and an upper surface of the air bag, JP-A-7-291078 discloses a method of fitting bosses protruded from a lower surface of an instrument panel of synthetic resin in mount holes, which are formed in a retainer of an air bag module, and then heat-clamping the bosses to fix the air bag module to the instrument panel.
Incidentally, in a case where a foam layer is provided between a skin and a base material of an instrument panel for a luxury specification, an air bag module can be securely fixed to the instrument panel by fixing the air bag module to a lower surface of the base material with bolts while avoiding the deterioration of the aesthetic appearance of the instrument panel by the bolts.
In addition, the air bag module can also be fixed to the instrument panel by heat claming bosses which are provided integrally on the lower surface of the base material so as to protrude therefrom.
In a case where the instrument panel is constructed as a single-layer instrument panel which does not have a foam layer, the fixing method uses the bolts which are exposed from the surface of the instrument panel, so that the fixing method has a problem that the aesthetic appearance of the instrument panel is deteriorated by the bolts.
In addition, processing time and costs become disadvantageous factors when the fixing method is used in which the bosses are heat clamped for fixing the air bag module to the instrument panel.
Furthermore, it is difficult to obtain a stable fixing strength due to change in processing conditions. Further, there is caused a problem that a surface sink is generated in the surface of the instrument panel at positions corresponding to the positions of the bosses, whereby the aesthetic appearance of the instrument panel is deteriorated.